A police officer appeared to punch a teenager in the face during an arrest struggle.
Shocking video footage has emerged of the incident, which took place in Scarborough, North Yorkshire.
In it, two police officers are seen restraining a teenager on the ground, with one of them kneeling on the boy.
The other cop appears to punch him squarely in the face, causing his head to bounce off the pavement.
Yorkshire Live reports that a bystander recorded the shock footage, which is reportedly in relation to a missing persons enquiry.
The boy can be heard saying: "You are battering me" in the video.
The incident is understood to have taken place in Eastborough at around 9.10pm on Friday [Sept 3].
It is understood North Yorkshire Police were responding to a report of a 17-year-old boy going missing from home when two officers were assaulted.
A 17-year-old boy has been arrested in connection with the incident.
In an earlier appeal, officers asked anyone in possession of mobile footage of the incident to contact them.
They also appealed for witnesses to the alleged assault to come forward.
Anyone wishing to make contact with police regarding the incident should dial 101, before pressing 1 to be passed to the force control room.
Callers should then quote reference number 12210194736.
